The catalysts with a base of copper and zinc oxides have been known since many years; they have been disclosed as early as 1933 by DODGE (U.S. Pat. No. 1 908 696). In the U.S. Pat. Nos. 3 388 972, 3 546 140 and 3 790 505, the American Company C.C.I. discloses the use of ternary compositions Cu-Zn-Al for the conversion at low temperature of carbon monoxide (CO) and for the synthesis of methanol. In the French Pat. No. 2 113 467 the SHELL Company recommends the use of Cu-Zn-Dy catalysts for the synthesis of methanol; Dy or didymium being the mixture of at least two oxides of rare earth metals having atomic numbers from 57 to 71 included. This company shows that the best results are obtained with catalysts containing several oxides of rare earth metals; the use of aluminum is not suggested.
Various methods for preparing Cu-Zn-Al catalysts are disclosed, particularly in the U.S. Pat. No. 3 923 694 (I.C.I.) and U.S. Pat. No. 4 279 781 (United Catalysts).
The addition of precious metals, as chlorides, has been claimed, in particular in the U.S. Pat. No. 4 257 920 which relates to Cu-Al-Zn catalysts prepared by admixing oxides and/or carbonates of said metals in the presence of an aluminous cement, the catalyst further containing at least one oxide of rare earth metals of atomic numbers from 57 to 71 included.